1. Technical Field
This invention relates to methods for preparing long chain α,ω-hydroxyacids and diacids and to oligomers and polymers comprising such compounds.
2. Prior Art
Microorganisms and their enzymes have long been utilized as biocatalysts in the preparation of various products. In recent years, there has been a growing interest in the use of microorganisms and their enzymes in commercial activities not normally recognized as being amenable to enzyme use.
Aliphatic polyesters are a group of biodegradable polymers that may be synthesized from readily renewable building blocks such as lactic acid- and fatty acid-derived materials. Aliphatic polyesters can be synthesized via polycondensation reactions between aliphatic dicarboxylic acids with diols, transesterification of diesters with diols, polymerization of hydroxy acids, and ring-opening polymerization of lactones. Resulting products can be used in industrial and biomedical applications such as for controlled release drug carriers, implants and surgical sutures. Moreover, polyesters with functional groups along chains or in pendant groups are attracting increased interest since these groups can be used to regulate polymeric material properties. Furthermore, functional polymers can be post-modified by attaching different biologically active groups that allow the preparation of biomaterials for use in drug delivery system and as scaffold materials for tissue engineering.
Both chemical and enzymatic approaches have been explored to synthesize functional polyesters. Chemical synthetic methods often require harsh reaction conditions and metal catalysts that are difficult to remove subsequent to polymerizations. Introduction of functional groups along chains or in pendant groups is difficult by chemical methods due to the lack of selectivity of chemical catalysts and associated harsh reaction conditions.
Polyesters, oligomers and polymers from ricinoleic acid have proven highly valuable for many applications, including controlled drug delivery systems. However, high purity ricinoleic acid can be expensive due to difficulties in its purification from the natural mixture. Currently, less costly α,ω-dicarboxylic acids are almost exclusively produced by chemical conversion processes. The chemical processes for production of α,ω-dicarboxylic acids from non-renewable petrochemical feedstocks usually produce numerous unwanted byproducts, require extensive purification, and give low yields (Bio/Technology 10: 894-898 (1992)). While several chemical routes to synthesize long-chain α,ω-dicarboxylic acids are available, their synthesis can be difficult, costly and requires toxic reagents.
Accordingly, there is a need for a process or method for producing ricinoleic acid analogs, which can have internal functionality that may consist of double bonds, triple bonds, epoxide, secondary hydroxyl, Si—O—Si and other moieties, in which the functional groups are transferred into the resulting dicarboxylic acids.